Keep it civil, do not flame or bait other users. If you notice anything illegal or inappropriate being discussed, contact an administrator or moderator.
Look through your uploaded pictures, notice that some have been tag-blanked, add the guys who did it to your list. See the pattern in the subject matter, check the uploads of other users who upload the same things, add more tag poisoners to your list.
They can remove the general tags, but they can't remove the id of the user who uploaded an image, or remove it from private or personal pools.
Make a personal pool with pictures that they tend to hit. The tag poisoners want to hide every single picture that they personally don't like from other users on the site, so they will tend to hit the select examples in your pool. Making the pool personal means that they can't easily see which images are the tripwires.
Muitsu tagged a TON of clearly non-child non-loli kasugano_sora images, as loli. Hope someone gives that idiot a vacation. I'm not gonna bother doing cleanup, he'd probably just reverse it.
He probably poisoned a lot of other images too. IMO, gelbooru should adopt danbooru's loli/child tagging policy, it makes searching much easier and more specific. If it ain't sexually suggestive, tag it child.
Muitsu has done that to some of my images as well; He's one of those people who tags anything with a small chest loli. Fragnostic did it before him, loli rating:safe is huge thanks to them.
I asked if loli should be used for safe images a long long time ago, Lozer did say safe images of actual kids should be tagged child.
EDIT: I just feel like clarifying I don't mean just actual real life children, just in case I somehow managed to confuse someone into thinking that.